Elastic fluid generator and the like



Jlxlvy Y1934- A. J. NERAD 1,965,427

ELASTIC FLUID GENERATOR AND THE LIKE Filed Aug. l2, 1932 2 Sheets-Sheetl His Atto-Wheg` July 3, 1934.4 A. J. NERAD g 1,955,427

ELASTIC FLUID GENERATOR AND THE LIKEA Filed Aug. l2, 1952 2 Sheets-Sheet2 Inventor: /Ambho'ng J. Nercld,

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Patented july 3, i934 ENT Friesl I Anthony J. Nerad, Schenectady, N. Y.,assigner to General Electric Company, a corporation of New YorkApplication Aiigust 12, 4193e, serial No. 628,519

l. Claim.

The present invention relates to elastic uid generators and likeapparatus in which a fluid is heated, vaporized and superheated.

In apparatus of this kind the fluid to be heated is contained incontainers such as drums and heating pipes or conduits. The heat istransmitted to the fluid containers mainly by radiation and conductionand the amount of heat thus transmitted depends upon the area of thesurfaces of the containers which are in contact with the heat carryingflames or gases.

It is known that in a small steam generating apparatus the heat releaseper cubic foot of furnace volume can be much greater than lin a largeone, owing to the greater cooling effect of a small steam generatingapparatus. A geometrical consideration shows that a small furnace has a.greater ratio of wall surface to volume than a large furnace of similarshape.

Since the heat absorption per unit area of the boiler tubes is the sameregardless of the size of the furnace, it is evident that combustion cantake place at a higher rate per unit volume in a small furnace owing tothe fact that a small furnace Oilers relatively more space for heatabsorbing Wall's and tubes at a high velocity of the fire gases than alarge size furnace.

The object of my invention is to provide an improved fluid-heatingapparatus such as an elastic fluid generating arrangement wherein theheat-absorbing surfaces are large in comparison with the dimensions ofthe entire apparatus. Such an apparatus is particularly advantageouswhere little space is available as in ships and airplanes.

For a consideration of what I consider to be novel and my invention,attention is directed to the following description and the claimappended thereto in connection with the drawings which form a part of myspecification.

In the drawings, Fig. 1 is a view, partly in cross section and partlydiagrammatic, of an elastic fluid generating arrangement embodying myinvention, the arrangement shown being one well adapted for use in amercury steam power plant; Fig. 2 is a cross section alorg`line 2--2,

Fig. 1, whereas Fig. 1 represents a section along line 1-1, Fig. 2; Fig.3 is a cross section of a part shown in Figs. 1 and 2 to an enlargedscale; and Figs. 4 and 5 illustrate a modification embodying myinvention, Fig. 4 being a section along line 4 4, Fig. 5 and Fig. 5 asection along line 5 5, Fig. 4.

Referring to Figs. 1 to 3, 6 designates the outer wall of a furnace orboiler. '7 is a conduit through which combustible material, for example,pulverized coal together with primary air, is fed to a plurality ofburners 8. Provided in the interior of the furnace are containers,including drums 9 and heating elements 10 containing a fluid such asmercury. The mercury is vaporized in these elements and drums, whichlatter are connected through conduits 11 to a header 12 supplying thevapor thus generated to a mercury turbine 13 having a valve 14 forregulating the admission of fluid in the usual manner. The heatcontained in the exhaust of the turbine is transmitted to another fluid,such as water, by the provision of a condenser boiler 15 connected tothe exhaust of the turbine. The mercury condensed in the condenserboiler is then fed by gravity or by means of a pump 16 through a conduit17 including a check valve 18 for preventing back flow of fluid, to alower header or headers 19 connected in series with elements 10 anddrums 9. The transmission 0f heat from the mercury to the water suppliedto the condenser boiler through a conduit 20 causes vaporization of thewater. The steam thus generated is conveyed from the condenser boilerthrough a conduit 21 to a superheater 22 subject to the heat of the fluegases,

-whence the superheated steam is conveyed through a conduit 23 to anykind of apparatus in which it is utilized. The flue gases afterpassingsuperheater 22 pass through a preheater 24 through which air isforced in a double pass by means of a blower or fan 25. The air leavingchamber 24 is conveyed to channels 26 having their lower partssurrounding the burners whereby this air assists the combustion of thefuel, acting as secondary air in the well known manner.

The apparatus so far described may be considered typical of any kind offluid heating or elastic fluid generating arrangements, particularly ofthose used in mercury steam plants where the heat contained in themercury vapor after leaving the turbine is submitted to a second medium,preferably water, for generating steam to be utilized in other turbinesor like consumers.

According to my invention, I provide an arrangement in which a pluralityof small combustion chambers are provided in order to obtain theadvantages of small fluid-heating apparatus as regards the ratio betweenthe area of the heatcontacting surfaces and the volume of the combustionchambers.

In the embodiment of Figs. 1 and 2, I have shown a plurality of chamberswhich are defined by the heating elements themselves. Figs. 1 and 2 showthree combustion chambers 27, 28 and 29 respectively. Each of thesechambers is deiined by heating elements 10. One of these elements isshown in Fig. 3 in cross section to an enlarged scale as comprising anouter corrugated casing wall 31 and a plurality of tubes 32 within thecasing embedded in a copper casting 33 filling the space defined betweenthe heating tubes and the outer 'I'his is a known construction forheating elements which has been used in mercury vapor generators. 'Iheseheating elements have the advantage that they provide for good heatconduction to the heating tubes and in the present instance they alsohave the advantage that they permit the omission of special walls fordeiining the diierent chambers. From Fig. 2 it will be readily seen thatthe walls between chambers 27, 28 and 29 respectively are defined by theheating elements themselves. Adjacent heating elements define clearances34 to permit expansion of the elements and at the same time anequalization of combustion in the different chambers. The heating tubesof the heating elements provided at the side Walls of each heatingchamber are directly connected into drums 9. The tubes of the heatingelements deflning the rear and front wall of each combustion chamberhave extensions 35 (Fig. 1) connected into equalizing conduits 36 whichlatter connect the different drums with each other. The lower portionsof the tubes of the heating elements have extensions connected to alower header or headers 19 by means of conduits 37 extending across theside walls of the heating chambers. To provide for good circulation ofthe iiuid to be heated in the elements and the drums, I connect thedrums by means of conduits 39 and 39a extending along the outside of thefurnace wall, with the lower header or headers 19. The combustionchambers are long and of comparatively small cross section. This causesa high velocity of the fuel particles burned therein. The verticalarrangement of the heating tubes results in a good heat distribution.

The heat contained in the gases escaping from the combustion chambers isutilized in a gas chamber, this term being used as a heat in thischamber is carried primarily by gases. Said chamber may also be termed aconduction chamber as the heating therein takes place primarily throughconduction between the gases and the elements to be heated in contrastto the combustion chamber where heating takes place primarily byradiation. As the temperature of the gases in the gas or conductionchamber is considerably lower than in the combustion chamber, I increasethe heating surface by increasing the number of heating tubes in thischamber. In the present example, I have shown a plurality of tube groups40, each comprising four 'tubes connected by separate upper headers 41.Four such tube groups form a row of tubes with the tubes of each rowconnected at their lower ends to a common lower header 42. In thepresent instance, I have shown nine rows of tubes. The upper headers ofthe groups are connected to drums 9`and the lower headers of the rows oftubes are connected to conduit 39a by means of conduits 44. The tube 39awhich in substance is a circulation tube, extending along the outside ofthe gas chamber, is connected to the drums 9 of the gas chamber. Thecirculating arrangement for the uid is not further described as anyknown arrangement may be provided for causing' the transmission of heatto the iiuid by convection.

The lower parts of the combustion and the gas chamber dene a space orintermediate chamber 46 having an opening 47 closed by a cover 48 forremoving slag and ashes. The gases during their passage from thecombustion to the gas chamber change their direction of flow, to theelect that great turbulence takes place within intermediate chamber 46,causing a complete combustion oi' the fuel. The heat contained in thegases leaving the gas or conduction chamber is absorbed in thesuper-heating chamber 22 and the secondary air-preheating chamber 24which are connected in series with the combustion and the conductionchamber as regards the flow of gases.

Whereas I have shown in Figs. 1 and 2 an arrangement in which thecombustion chamber and the gas chamber are provided adjacent each otherwith an intermediate chamber for connecting them to each other, I haveshown in Figs. 4 and 5 an arrangement in which the gases leaving thecombustion chamber 'low directly into the conduction or gas chamber.

Referring more speciically to the arrangements illustrated in Figs. 4and 5, 50 designates a furnace or boiler wall having a lower space inwhich a plurality of heating elements 51 are provided in a manner todefine a plurality of combustion chambers 52, 53, 54 and 55. 'I'hearrangement of the heating elements dei-ined in these chambers issubstantially the same as that shown in the left hand part of Figs. 1and 2. The tubes of each element are connected together at their upperends as indicated at 56 of Fig. 4 to one end of conduits 57 having theirother ends connected to drums 58. The lower ends of the heating tubesare connected through conduits 59 to a header 60 which in turn, throughtubes 61 extending along the outside of. the furnace, is connected tothe drums 58. The upper space of the boiler defining a conduction or gaschamber into which the gases escaping from the combustion chamber passis provided similarly to the arrangement shownfin Fig. 1 with a greaternumber of tubes. A plurality of tubes with their upper ends connectedtogether by headers 62 deiine groups 63. A plurality of groups, in thepresent instance four, dene rows of groups with the tubes defining thegroups connected together at their lower ends to a common header 64. Thelower headers 64 are connected to the circulating pipes 61 whereas theupper headers 62 of each group are connected through conduits 65 to thedrums 58. The latter are connected together by means of conduits 66 to amain header 67 from which elastic fluid may be supplied to a turbine orlike apparatus as described in connection with Fig. 1. Make-up orcondensed fluid is supplied to the lower headers in the combustion andthe conduction chamber through a conduit 68. The arrangement shown inFigs. 4 and 5, due to its compactness, is particularly adapted toairplane and like installations where little space is available.

Having described the method of operation of my invention, together withthe apparatus which I now consider to represent the best embodimentthereof, I desire to have it understood that the apparatus shown is onlyillustrative and the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is,--

In an elastic iiuid generating arrangement, a plurality of verticalwalls defining a combustion and a gas space, heating elements in thecombustion space arranged to dene a plurality of including upper headersconnected to. the drums, lower headers for the groups connecting thelower ends of the tubes of a plurality of groups tcgether to deiine rowsof groups, means for permitting circulation of fluid between the drumsand the lower headers of the rows oftubes and the elements respectively.

' ANTHONY. J. NERAD.

